My blood pressure is 108/71. is that too low?

It's fine. Many young adults have even lower BP's.. I've had healthy young women who had blood pressures like 90 /60. Presence of symptoms like lightheadedness are a sign that blood pressure may be too low

That is a normal blood pressure, normal range applies mostly to higher values, low blood pressure becomes an issue if possible symptoms related to it and in emergencies when the cause is usually different.

No. As long you do not have any symptoms, such as dizziness on standing, it is a good blood pressure. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV, Flu and Covid vaccines. Wish you good health!